High-frequency circuit device and high-frequency circuit module
A high-frequency circuit device includes a dielectric member 1, a shielding conductor 2 surrounding the dielectric member 1, a support member 3 for fixing and supporting the dielectric member 1, and a pair of transmission lines 4 each of which is formed of a microstrip-line. Each of the transmission lines includes a substrate 6 formed of a dielectric material, a strip conductor 5, and an earth conductor layer 9. An end portion of the strip conductor 5 faces part of the dielectric member 1 and functions as a coupling probe for input/output coupling. Each of the transmission lines 4 is formed of a strip line, a mictostrip line, a coplanar line or the like, and has low-loss when connected to a circuit board.
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This application is a divisional of U.S. patent application Ser. No. 10/466,508 filed on Jul. 17, 2003, now U.S. Pat. No. 6,954,124 which is a National Phase of PCT/JP02/00372 filed Jan. 21, 2002. This application also claims the benefit of Japanese Patent Application Nos. 2001-011244 filed Jan. 19, 2001 and 2001-176603 filed Jun. 12, 2001. The disclosure(s) of the above application(s) are incorporated herein by reference.
TECHNICAL FIELDThe present invention relates to high-frequency circuit devices and modules for resonance used in radio-communication systems or other devices dealing with high-frequency signals.
BACKGROUND ARTConventionally, high-frequency filters and other high-frequency circuit devices including a resonant body as a basic element are essential for communication systems. With a resonant body, among resonator bodies, using a dielectric material such as a high dielectric constant, low-loss ceramic material, a high-frequency circuit device functioning as a small and low-loss (high-Q) resonator can be achieved.
Such a resonator can be disposed with other circuit elements such as an amplifier, an oscillator, and a mixer circuit on a substrate to make a high-frequency circuit have a module configuration. In this case, a high-frequency signal needs to be input/output to/from the resonator via a transmission line such as a stripline on the substrate. As an example of such high-frequency circuits using a dielectric material, a circuit in which a dielectric member is disposed on a circuit board and then a stripline around the member and thereby a high-frequency signal is input/output from/to a resonator is known, as disclosed, e.g., in Japanese Unexamined Patent Publication 10-284946.
In this case, the dielectric member has a circular cross section and resonates in the TE01δ mode. The dielectric member is used for the purpose of transmitting only a desired frequency element of a high-frequency signal from the stripline, or removing unnecessary frequency elements.
Problems to be Solved
However, the above-described known high-frequency circuit in which a dielectric member is disposed on a substrate has the following problems.
First, since the dielectric member is used without being shielded, high-frequency signals (electromagnetic waves) from the dielectric member are emitted. The signal emission may cause an increase in the loss of a resonator, i.e., a reduction in the Q value of the resonator. Moreover, by the emitted electromagnetic waves, the dielectric member may be coupled with other circuits disposed on a substrate to make circuit operation unstable. Furthermore, in order to suppress the coupling between the dielectric member and other circuits by the emitted electromagnetic waves, it is necessary to dispose the dielectric member so as to be spaced apart from the other circuits by a certain distance. This is an obstacle to reduce the size of an entire module.
The above-described problems are more clearly noticed, as the frequency of high-frequency signals dealt with in a high-frequency circuit device is increased. Therefore, they may be fatal problems in a millimeter wave band or the like.
Moreover, in a TE01δ mode resonator, the distribution of the resonant electric field may show a concentric configuration in a cylindrical dielectric member. Therefore, it may be difficult to obtain a desired coupling of the dielectric member with a stripline or the like disposed on the substrate.
DISCLOSURE OF INVENTIONIt is therefore an object of the present invention to provide low-loss, high-frequency circuit device and module in which a dielectric member is incorporated.
A high-frequency circuit device according to the present invention includes: at least a dielectric member which can create a resonant state of an electromagnetic wave; a shielding conductor surrounding the dielectric member; at least a transmission line including a strip conductor disposed to face part of the dielectric member, an earth conductor layer disposed to face the strip conductor, and a dielectric layer interposed between the strip conductor and the earth conductor layer; and a coupling probe which is connected to the transmission line and has the input/output coupling function of input/output coupling with the dielectric member by an electromagnetic wave.
Thus, the dielectric member is surrounded by the shielding member. Accordingly, emission of an electromagnetic wave from the dielectric member to the outside thereof is blocked and also it is possible due to the structure of the transmission lines to make smooth connection with other semiconductor devices or the like in the high-frequency circuit. That is to say, functions which have been achieved with a waveguide or the like can be attained on a circuit board. Therefore, the size of an entire high-frequency circuit which has low-loss, i.e., a large Q value and in which a high-frequency circuit device is disposed can be reduced.
The dielectric member is excited in a TM mode. Therefore, in a TM mode resonator, the electric field extends along the longitudinal direction of the dielectric member and thus the dielectric member can be coupled with the strip conductor of each said transmission line in a simple manner. Accordingly, each said transmission line having the strip conductor can be used for the input/output. Therefore, by disposing the transmission lines with the high-frequency circuit on a substrate, the transmission lines can be applied to a high-frequency circuit having a module configuration in an easy manner.
The transmission line preferably includes at least one of a stripline, a microstrip-line, a coplanar line and a microwire line.
If the inventive high-frequency circuit device further includes within the shielding conductor an insulating layer which is filled in the space between the shielding conductor and the dielectric member and supports the dielectric member, a stable resonance state of the dielectric member can be achieved.
If the shielding conductor is formed of a conductive coating film on the outside surface of the insulating layer, the strip conductor is formed of the conductive coating film so as to be separated from the shielding conductor, and part of the conductive coating film facing the strip conductor functions as the earth conductor layer, process steps for fabricating the high-frequency circuit device can be simplified and production costs can be reduced.
The earth conductor layer may form a wall portion that is to be part of the shielding conductor, and the high-frequency circuit device may further includes a groove formed in the earth conductor layer and an insulating support substrate which is formed on the earth conductor layer so as to be located over the groove and supports the dielectric member.
Said at least a transmission line may be a pair of transmission lines and the high-frequency circuit device may function as a bandpass filter.
In that case, an end portion of the strip conductor may extend so as to protrude outward from the dielectric layer and function as the coupling probe, or the end portion of the strip conductor may be located on the dielectric layer and function as the coupling probe.
The end portion of the strip conductor is preferably bent in the direction in which the degree of input/output coupling is increased.
Specifically, when a main portion of the strip conductor extends perpendicularly to the longitudinal direction of the dielectric member, the part of the strip conductor preferably extends almost in parallel to the longitudinal direction of the dielectric member.
Said at least a transmission line may be a continuous line and the high-frequency circuit device functions as a band stop filter.
In that case, part of the strip conductor other than the end portion faces the dielectric member and functions as the coupling probe.
The part of the strip conductor is preferably bent in the direction in which the degree of input/output coupling is increased.
Specifically, when a main portion of the strip conductor extends perpendicularly to the longitudinal direction of the dielectric member, the part of the strip conductor preferably extends almost in parallel to the longitudinal direction of the dielectric member.
If the inventive high-frequency circuit device further includes: a dielectric substrate; and a first conductive film which is formed on a surface of the dielectric substrate facing the dielectric member and is to be part of the shielding conductor, process steps for fabricating the high-frequency circuit device can be simplified.
The dielectric member is, e.g., a square pole or a circular cylinder.
The shape of the dielectric member's cross section perpendicular to the longitudinal direction thereof changes so that the cross section has the largest area at a center portion of the dielectric member. Thus, the size of the high-frequency circuit device can be reduced.
Said at least a dielectric member may be a plurality of dielectric members coupled with each other.
If the inventive high-frequency circuit device further includes a frequency adjustment screw which is inserted through the shielding conductor into a region of the high-frequency circuit device surrounded by the shielding conductor and has an end facing the dielectric member, frequency properties can be more finely adjusted.
When said at least a dielectric member is a plurality of dielectric members coupled with each other, the high-frequency circuit device further includes an inter-stage coupling adjustment screw which is inserted through the shielding conductor into a region of the high-frequency circuit device surrounded by the shielding conductor and has an end facing the space between adjacent ones of the dielectric members. Thus, an inter-stage coupling state can be more finely adjusted.
A high-frequency circuit module according to the present invention includes: a plurality of high-frequency circuit devices; and a phase shift circuit provided between adjacent ones of the plurality of the high-frequency circuits, each said high-frequency circuit device includes: at least a dielectric member which can create a resonant state of an electromagnetic wave; a shielding conductor surrounding the dielectric member; at least a transmission line including a strip conductor disposed to face part of the dielectric member, an earth conductor layer disposed to face the strip conductor, and a dielectric layer interposed between the strip conductor and the earth conductor layer; and a coupling probe which is connected to the transmission line and has the input/output coupling function of input/output coupling with the dielectric member by an electromagnetic wave, and the transmission line of each said high-frequency circuit device is connected to the phase shift circuit.
Thus, a small-size, low-loss resonator (which multiplexes or separates transmission/reception signals having different frequencies) can be achieved. Thus, functions which have been achieved with a waveguide or the like can be attained on a circuit board.
When the respective center frequencies of the plurality of high-frequency circuit devices in a resonant state are different to each other, the high-frequency circuit module can perform processing.
For example, when the phase shift circuit is connected to an antenna, it is possible to simultaneously transmit and receive signals by utilizing the plurality of high-frequency circuit devices.
Moreover, each of the transmission lines 4 includes a transmission-line substrate 6 formed of polytetrafluoroethylene resin or the like, a strip conductor 5 formed of a silver ribbon or the like on the upper surface of the transmission-line substrate 6, and an earth conductor layer 9 for supporting the transmission-line substrate 6 at the underside surface. The earth conductor layer 9 is formed of part of the shielding conductor 2. Each of the transmission lines 4 is inserted into a region of the high-frequency circuit device surrounded by the shielding conductor through part of the shielding conductor 2. More specifically, a window is formed in part of a side wall of the shielding conductor 2 perpendicular to the longitudinal direction of the shielding conductor 2, each of the transmission lines 4 is inserted into the window and the upper surface of each of the transmission lines 4 is covered with an insulator 7 at a window portion. The insulator 7 is provided to prevent a short-circuit of the strip conductor 5 to the shielding conductor 2. In the shielding conductor 2, an end portion of each of the strip conductor 5 protrudes outward from the insulator substrate 6 and faces the side surface perpendicular to the longitudinal direction of the dielectric member 1 so as to form a coupling probe portion 8. The coupling probe portion 8 exhibits the input coupling function or the output coupling function, with respect to the dielectric member 1, according to the direction in which a high-frequency signal is transmitted.
Note that although not shown in the drawings, in this embodiment or other embodiments which will be described later, the transmission lines 4 are connected to various circuits (e.g., an amplifier, a voice converter circuit, and an image converter circuit) disposed on a circuit board.
In this embodiment, the earth conductor layer 9, which is also part of the shielding conductor 2, serves as a ground plane of the transmission lines 4. Therefore, to connect each of the transmission lines 4 and an external circuit to each other, only application of a signal voltage between the strip conductor 5 and the earth conductor layer 9 is required. Thus, it is possible to suppress signal loss to a lower level.
In the structure of the high-frequency circuit device of this embodiment, it is possible to make the dielectric member 1 resonate in a resonator mode called “TM11δ mode” for a resonator with a rectangular cross section by appropriately selecting shapes and materials for the dielectric member 1, the shielding conductor 2 and the support member 3. Thus, with the high-frequency circuit device of this embodiment, a TM11δ mode resonator can be achieved. Also, the high-frequency circuit device of this embodiment can be used as a single-stage bandpass filter.
In this case, the TM11δ mode of the resonator with a rectangular cross section using dielectric member having a rectangular cross section is equivalent to the TM11δ mode of the resonator with a circular cross section using a cylindrical dielectric member. In the resonator with a rectangular cross section, the first two subscrips of a mode name (i.e., 11 or 01 herein) are determined based on the periodicities of the magnetic fields in the directions in which the sides of the rectangular cross section of the resonator extend. In contrast, in the resonator with a circular cross section, the subscrips are determined based on the periodicities of the magnetic fields in the circumferential direction and in the radial direction.
SECOND EMBODIMENTNote that as shown in
A high-frequency circuit device having the structure shown in
Qu={f0/|f1−f2|}[1/{1−10−L0/20}]
In this manner, the no-load Q value was obtained.
Moreover, it has been confirmed that the actually measured value for the no-load Q value (Qu) when the ceramic material of this specific example is used can be improved so as to reach about 1000 by finely adjusting the structure of the high-frequency circuit device.
As will be described later, it has been also confirmed that with some other low-loss ceramic material, the no-load Q value is improved.
Considering that the Q value of a half wavelength resonator using a general microstrip-line is about 100, the actually measured no-load Q values are very high and thus it is shown that with the high-frequency circuit device of this embodiment, a very-low-loss resonant circuit can be formed. In particular, if the high-frequency circuit device of this embodiment is applied to a circuit element such as a resonator or a filter in a millimeter wave band, higher effects can be achieved.
Note that this specific example is an example for the structure of the second embodiment. However, even though this example is used for the structure of the first embodiment, almost the same results can be obtained.
THIRD EMBODIMENTThe high-frequency circuit device of this embodiment can function as a low-loss, two-stage bandpass filter, as has been confirmed in a specific example which will be descried hereinafter.
SPECIFIC EXAMPLE OF THIRD EMBODIMENTA high-frequency circuit device having the structure shown in
In the structure of the high-frequency circuit device of this embodiment, as in the high-frequency circuit device of the second embodiment (see
Note that instead of the two dielectric members of this embodiment, three or more dielectric members can be disposed. That is to say, the high-frequency circuit device can be utilized as a multi-stage bandpass filter.
FOURTH EMBODIMENTIn this embodiment, the end portion of the strip conductor 5 located on the transmission-line substrate 6 as it is can be used as a coupling probe 8. Thus, besides the same effects as those of the first embodiment, the structure of a portion of the circuit being input/output coupled can be advantageously simplified.
Note that in the structure of the high-frequency circuit device of this embodiment, the degree of input/output coupling can be adjusted according to the height or lateral direction positional relationship between the transmission-line substrate 6 and the dielectric member 1. For example, there is a tendency that as the space between the transmission-line substrate 6 and the dielectric member 1 is reduced so that they get closer to each other, the degree of input/output coupling increases. As the transmission-line substrate 6 is closer to a center portion of the dielectric member 1, the input/output coupling degree tends to decrease. The high-frequency circuit device of this embodiment, as that of the first embodiment, can function as a resonator and be used as a low-loss, single-stage bandpass filter.
Note that in this embodiment, as an exemplary high-frequency circuit device, the high-frequency circuit device in which a dielectric member is disposed has been described. However, two dielectric members 1a, 1b may be disposed as in the third embodiment, or three or more dielectric members may be disposed. That is to say, the high-frequency circuit device can be utilized as a two-stage or multi-stage bandpass filter.
FIFTH EMBODIMENTIn this embodiment, the end portion of the strip conductor 5 located on the transmission-line substrate 6 as it is can be used as the coupling probe 8. Thus, the structure of input/output coupled parts of the circuit device can be advantageously simplified as in the fourth embodiment.
Particularly, in this embodiment, if the end portion functioning as a coupling probe is bent in the direction in which the degree of input/output coupling is increased, a highly effective resonator can be achieved. For example, if the bent end portion 10 is lengthened so as to be longer than a shorter side of the dielectric member 1, the input/output probe 8 can have a greater length than that of the fourth embodiment. Thus, with the high-frequency circuit device of this embodiment, elements in the electric field of a resonator mode can be effectively condensed to achieve a higher degree of in put/output coupling than that in the fourth embodiment. Moreover, the degree of the condensation can be advantageously adjusted with a fixed positional relationship between the transmission-line substrate 6 and the dielectric member 1 according to the length L of the end portion 10. The high-frequency circuit device of this embodiment, as that of the first embodiment, can function as a resonator and be used as a low-loss, single-stage bandpass filter.
SPECIFIC EXAMPLE OF FIFTH EMBODIMENTA high-frequency circuit device having the structure shown in
It has been actually confirmed from results of measurements using a network analyzer that a resonance event occurs at around 26 GHz. This shows that the high-frequency circuit device can not only operate as a resonant circuit but also be utilized as a single-stage bandpass filter. The no-load Q value of the resonance was about 1000.
The high-frequency circuit device of this embodiment can function as a low-loss, two-stage bandpass filter, as has been confirmed in a specific example which will be descried hereinafter.
With the circuit of this embodiment, if the coupling structure of the fifth embodiment can be utilized as a multi-stage bandpass filter, greater effects can be attained. The reason for this is as follows. In a bandpass filter, normally, it is preferable that the input/output coupling degree is relatively high and the coupling degree is accurately controlled to achieve desired properties.
Note that in this embodiment, an exemplary high-frequency circuit device functioning as a two-stage bandpass filter has been described. However, it is also very effective that three or more dielectric members are used and thus the high-frequency circuit device is utilized as a three-stage or multi-stage bandpass filter.
SPECIFIC EXAMPLE OF SIXTH EMBODIMENTA high-frequency circuit device having the structure shown in
Note that in this embodiment, the case where a dielectric member 1 is provided has been described. However, with a plurality of dielectric members 1 provided, when the high-frequency circuit device is applied to a multi-stage band stop filter, this embodiment is also effective.
EIGHTH EMBODIMENTIn addition, in the high-frequency circuit device of this embodiment, the bent portion 11 of the strip conductor 5 extends in the longitudinal direction of the dielectric member 1. Thus, the direction of the electromagnetic field of the resonator mode matches that of the transmission line 4 at the bent portion 11. Accordingly, a very large coupling can be achieved between the electromagnetic wave transmitting through the transmission line 4 and the electromagnetic field of the resonator mode, thus resulting in strong blocking properties.
Note that in this embodiment, the case where a dielectric member 1 is provided has been described. However, with a plurality of dielectric members 1 provided, when the high-frequency circuit device is applied to a multi-stage band stop filter, this embodiment is also effective.
SPECIFIC EXAMPLE OF EIGHTH EMBODIMENTA high-frequency circuit device having the structure shown in
In this embodiment, a groove 13 which extends in the longitudinal direction of an earth conductive layer 9 is formed. The inside of the groove 13 is empty. Moreover, the inside of a shielding conductor 2 is also empty. The dielectric member 1 is placed on the dielectric substrate 12 over the groove 13. That is to say, the dielectric substrate 12 functions as a support member for supporting the dielectric member 1 in this embodiment.
Moreover, each of transmission lines 4 includes a transmission-line substrate 6, a strip conductor 5 formed of a silver ribbon or the like, and the earth conductor layer 9 which is a part of the shielding conductor 2. Each said transmission line 4 is inserted to a region of the high-frequency circuit device surrounded by the shielding conductor through the part of the shielding conductor 2. More specifically, a window is formed in part of a side wall of the shielding conductor 2 perpendicular to the longitudinal direction of the shielding conductor 2, the transmission line 4 is inserted into the window and the upper surface of the transmission line 4 is covered with an insulator 7 at a window portion. The insulator 7 is provided to prevent a short-circuit of the strip conductor 5 located on the transmission-line substrate 6 to the shielding conductor 2. In the inside of the shielding conductor 2, the strip conductor 5 extends on the dielectric substrate 12 and an end portion 10 thereof is bent through almost 90 degree to form an L shape. The end portion 10 of the strip conductor 5 faces a side surface of the dielectric member 1 extending in its longitudinal direction. The end portion 10 functions as a coupling probe.
In this embodiment, the earth conductor layer 9, which is a part of the shielding conductor 2, serves as a ground plane. Therefore, to connect each of the transmission lines 4 and an external circuit to each other, only application of a signal voltage between the strip conductor 9 and the earth conductor layer 9 is required. Thus, it is possible to suppress signal loss to a low level.
In the structure of the high-frequency circuit device of this embodiment, it is possible to make the dielectric member 1 resonate in a resonator mode called “TM11δ mode” for a resonator with a rectangular cross section by appropriately selecting shapes (and materials) for the dielectric member 1, the shielding conductor 2, the dielectric substrate 12, and the groove 13. Thus, with the high-frequency circuit device of this embodiment, a TM11δ mode resonator can be achieved. Also, the high-frequency circuit device of this embodiment can be used as a single-stage bond pass filter.
Specifically, with the high-frequency circuit device of this embodiment, this embodiment is characterized in that the transmission-line substrate 6 and the dielectric substrate 12 can be unified and the support member 3 of the first through eighth embodiments is not necessarily provided because the dielectric member 1 is fixed by the dielectric substrate 12, as can be seen from
Note that each of the transmission lines 4 may be inserted from the front or back of the dielectric member 1 in this embodiment.
Furthermore, the groove 13 is not necessarily provided. Even though the groove 13 is not provided and the underside surface of the dielectric substrate 12 is in direct contact with an inside wall of the shielding conductor 2, a resonator which can operate in the same manner as that of this embodiment can be obtained. However, if the shielding conductor 2 is in contact with part of the underside surface of the dielectric substrate 12 located directly under the dielectric member 1, a large high-frequency current may flow, causing an increase in the loss. In contrast, if the groove 13 is provided as shown in
Moreover, in the high-frequency circuit device of this embodiment shown in
Moreover, it is also effective to form the coupling probe 8 on the underside surface of the dielectric substrate 12. In this case, if the coupling probe 8 is formed directly under the dielectric member 1, a large coupling amount can be achieved. However, in this case, in order to electrically connecting the dielectric member 1 and the strip conductor 5 to each other, it is necessary to make the strip conductor 5 on the surface of the dielectric substrate 12 and the coupling probe 8 on the underside surface of the dielectric substrate 12 capacitively coupled with a capacitance interposed therebetween, or to form the strip conductor 5 on the underside surface of the transmission-line substrate 6.
Moreover, in the structure of this embodiment, as in the seventh or eighth embodiment (see
Moreover, in this embodiment, it is more preferable to use as the dielectric substrate 12 a material having a lower dielectric constant than that of the dielectric member 1. For example, assume that a material having a relative dielectric constant of 20 or more is used as the dielectric member 1. When characteristics and the structure of the high-frequency circuit device of this embodiment are taken into consideration, the use of an alumina substrate or some other dielectric substrate having a relatively low dielectric constant is effective.
TENTH EMBODIMENTAs shown in
In this embodiment, the strip conductor 5 and the conductive coating film 17 together form a coplanar stripline in a region Rco. Therefore, when the high-frequency circuit device is intended to be connected with an external circuit, a signal voltage may be applied between the srtip conductor 5 and the conductive coating film 17.
In the structure of the high-frequency circuit device of this embodiment, it is possible to make the dielectric member 1 resonate in a resonator mode called “TM11δ mode” for a resonator with a rectangular cross section by appropriately selecting shapes and materials for the dielectric member 1, the conductive coating film 17 and the support member 3. Thus, with the high-frequency circuit device of this embodiment, a TM11δ mode resonator can be achieved. Also, the high-frequency circuit device of this embodiment can be used as a single-stage bandpass filter.
In addition, in the high-frequency circuit device of this embodiment, the strip conductor 5 that forms the transmission lines 4, and the conductive coating film 17 that is a ground plane can be formed on a single plane. Thus, surface mounting can be performed in a simple manner.
Note that in the high-frequency circuit device of this embodiment, the transmission lines 4 can be formed laterally with respect to the dielectric member, as in the second embodiment (see
Moreover, each of the transmission lines 4 includes the dielectric substrate 20, a strip conductor 5 formed of a portion separated from the conductive coating film 17, and the earth conductor layer 9 supporting the dielectric substrate from the underside surface thereof. The conductive coating film 17 and the earth conductor layer 9 are electrically connected to each other through a via hole 21 passing through the dielectric substrate 20. Then, each of the transmission lines 4 is inserted into a region of the high-frequency circuit device surrounded by the shielding conductor through part of the shielding conductor 2. More specifically, a window is formed in part of a side wall of the shielding conductor 2 perpendicular to the longitudinal direction of the shielding conductor 2, each of the transmission lines 4 is inserted into the window, and the upper surface of each of the transmission lines 4 is covered with an insulator 7 at a window portion. The insulator 7 is provided to prevent the short-circuit of the strip conductor 5 to the shielding conductor 2. In the shielding conductor 2, a pointed-end potion of the strip conductor 5 faces the underside surface of the dielectric substrate 20 (and also faces a side surface of the dielectric member 1 extending perpendicularly to the longitudinal direction) to function as a coupling probe portion 8.
In this embodiment, the earth conductor layer 9, i.e., a part of the shielding conductor 2 serves as the ground plane of the transmission lines 4. Therefore, to connect the transmission line 4 and an external circuit, only application of a signal voltage between the strip conductor 5 and the earth conductor layer 9 is required. Thus, it is possible to suppress signal loss to a lower level.
In the structure of the high-frequency circuit device of this embodiment, it is possible to make the dielectric member 1 resonate in a resonator mode called “TM11δ mode” for a resonator with a rectangular cross section by appropriately selecting shapes and materials for the dielectric member 1, the shielding conductor 2, the dielectric substrate 20, and the support member 3. Thus, with the high-frequency circuit device of this embodiment, a TM11δ mode resonator can be achieved. Also, the high-frequency circuit device of this embodiment can be used as a low-loss, single-stage bandpass filter.
Moreover, in the high-frequency circuit device of this embodiment, the strip conductor 5 and the conductive coating film 17 can be formed of a common metal film. Thus, the number of parts to be assembled can be reduced and therefore variations in properties resulting from variations among assembled parts can be advantageously suppressed.
Note that in this structure, the transmission lines 4 can be formed laterally with respect to the dielectric member 1 as shown in
With the structure of high-frequency circuit device of this embodiment, the electromagnetic distribution around the dielectric members 1a, 1b is adjustable. More specifically, the resonance frequency of a resonator and the degree of a coupling between resonators can be adjusted by changing the insertion amounts of the frequency adjustment screws 14 and 15, and the insertion amount of the inter-stage coupling adjustment screw 16, respectively. Thus, deterioration of properties of a high-frequency circuit device due to mis-measurements in processing and assembling steps can be recovered by adjustments performed after the high-frequency circuit device has been fabricated. Therefore, efficiency in fabrication process steps can be greatly improved.
Note that in this embodiment, the structure of the two-stage bandpass filter has been described as an example. However, this embodiment is not limited thereto, but is applicable to a single-stage filter, or a three- or more-stage filter.
Frequency and inter-stage adjustments do not have to be performed using the screws but may be done using other members such as a pole-shape or plate-shape member having the same function as that of the screws.
Moreover, in the first through eleventh embodiments, adjustments for the resonance frequency and inter-stage coupling degree of the circuit can be performed using members such as a screw. In such a case, the same effects as those of this embodiment can be attained.
Note that if frequency adjustment screws are disposed so as to have the same positional relationship and the same axial direction as those of the frequency adjustment screws 14, i.e., each of the screws is disposed to face an end portion of an associated one of the dielectric members 1a, 1b, frequency can be effectively adjusted as has been described in this embodiment. On the other hand, if three or more stages of dielectric members are provided, the frequency adjustment using such screws is applicable only to frequency adjustment for dielectric members located at both ends. Then, it is effective that a frequency adjustment screw is provided perpendicularly to each of dielectric members in the same manner where the frequency adjustment screws 15 are disposed. More precisely, it is effective to dispose a frequency screw perpendicularly to the direction in which the electric field of a TM mode extends. Moreover, as for the insertion position of each of the frequency adjustment screws, it is the most effective that a frequency adjustment screw is inserted so as to face a portion of each said dielectric members 1a, 1b which has the strongest electric field, i.e., a center potion of each of the dielectric members 1a, 1b in this embodiment. In this case, frequency adjustment using the frequency adjustment screws is also advantageously applicable to a high-frequency circuit device in which three- or more-stage dielectric members are disposed.
SPECIFIC EXAMPLE OF TWELFTH EMBODIMENTA high-frequency circuit device having the structure shown in
As can be seen from
Note that each of the high-frequency circuit devices is connected to a processing circuit by a switch. Signal processing such as signal amplification or signal transformation into a sound or image signal is performed in the processing circuit.
In the high-frequency circuit module of this embodiment, a plurality of the high-frequency circuit devices are provided with the phase shift circuit interposed therebetween. In other words, a small-size, low-loss common apparatus (which multiplexes or separates transmission/reception signals having different frequencies) can be achieved. Thus, functions which have been achieved with a known waveguide or the like can be attained on a circuit board.
For example, when a phase shift circuit is connected to an antenna, a signal can be transmitted or received. More specifically, when two high-frequency circuit devices having different center frequencies are combined with a phase shift circuit interposed therebetween, the effects of the first embodiment are maintained and also signals can be simultaneously transmitted and received.
Note that in this embodiment, as an exemplary common apparatus, a single-stage to single-stage type common apparatus has been described. However, if a plurality of dielectric members are used in at least one of the bandpass filters (i.e., the high-frequency circuit devices A and B), it is effective to utilize the common apparatus of this embodiment as a common apparatus including a multi-stage band filter.
SPECIFIC EXAMPLE OF THIRTEEN EMBODIMENTA high-frequency circuit module having the structure shown in
Also, in the high-frequency circuit device B (bandpass filter), two dielectric ceramic square poles (having a relative dielectric constant of 21 and a fQ value of 70000 GHz), as dielectric members 1d, 1f, each of which has dimensions of 1×1×5.8 mm, and a dielectric ceramic square pole (having a relative dielectric constant of 21 and a fQ value of 70000 GHz), as a dielectric member 1e, which has dimensions of 1×1×5.6 mm are prepared. Then, the dielectric members 1d through 1f are fixed in a shielding conductor 2b formed of a zinc-copper alloy and having inside walls plated with gold. The dimensions of the inside of the shielding conductor 2b is 3×3×25.7 mm.
Then, polytetrafluoroethylene resin is used as support members 3a, 3b to be filled in the space between the shielding conductor 2a and each of the dielectric members 1a through 1c and the space between the shielding conductor 2b and each of the dielectric members 1d through 1f, respectively. As for transmission lines 4, strip conductors 5a, 5c (having a characteristic impedance of 50Ω) of a gold film (having a thickness of 10 μm and a width of about 0.3 mm) are formed on a transmission-line substrate 6 made of sintered alumina. Then, the strip conductors 5a, 5c are extended so as to protrude outward from the insulator substrate 6 and reach the insides of the shielding conductors 2a, 2b, respectively. These extended portions are to be coupling probes 8.
Moreover, as for a phase shift circuit 18, the strip conductor 5b made into a certain pattern is formed on a phase shift circuit board 19 formed of a polytetrapluoroethylene resin substrate. More specifically, the phase shift circuit 18 is made into a T shape pattern formed by a main portion and two branch portions. The width of the strip conductor 5b is set to be 0.5 mm so that the characteristic impedance of the circuit is around 50 Ω.
Note that the phase shift circuit 18 has the functions of separating and multiplexing signals by appropriately setting the length of each of the strip conductors to make the cross-band of each of the branch portions substantially in an electrically open state.
Moreover, in this structure, transmission lines 4 can be disposed in series with the dielectric members 1a, 1b in the longitudinal direction of the dielectric members 1a, 1b as shown in
Moreover, in this embodiment, as an exemplary common apparatus, the common apparatus which multiplexes or separates transmission/reception signals in two frequency bands has been described. However, the high-frequency circuit module of the present invention is not limited to the structure of this embodiment but is also effective in the case where signals in three or more frequency bands are multiplexed or separated. In such a case, as the pattern of the phase shift circuit 18 on the phase shift circuit board 19, a pattern having as many branch portions as the number of frequency bands of signals to be multiplexed or separated may be used. If the number of branches is too many, it is effective to use a branched pattern in which a plurality of two-branch lines as shown in
In each of the above-described embodiments, the dielectric square pole with a rectangular cross section of the TM11δ mode is used for the dielectric member 1. However, the present invention is not necessary limited to the structure. Even when a dielectric circular cylinder with a circular cross section is used, the same effects as those of each of the embodiments can be attained. It is a common practice to call a resonator mode in this case “TM01δ mode”. Moreover, the shape of a dielectric member's cross section has been described by taking as an example a dielectric member with a uniform cross section along their length direction, i.e., along the direction in which the electric field inside of the dielectric member extends. However, even if the shape of cross section of the dielectric member is partially changed, the present invention is also effective.
Moreover, in the specific example of each of the embodiments except for the thirteenth embodiment, the dielectric member 1 is formed of a material containing ZrO2—TiO2—MgNb2O6 as a main component (having a relative dielectric constant of 42.2 and a fQ value of 43000 GHz). However, a material for the dielectric member 1 is not necessarily limited to the material. When a material having a higher dielectric constant than that of the support member 3 is used as the dielectric member 1, the TM11δ mode appears and thus the effects of this embodiment can be reliably attained.
Moreover, the Q value of a resonator is largely influenced by dielectric loss of a material forming the dielectric member 1. Therefore, it is preferable to use as the dielectric material a low-loss material (i.e., a material having a large fQ value). Furthermore, if a material having a high dielectric constant is used, the dielectric member 1 may have a small length and a small diameter to obtain the same resonance frequency. Therefore, the size of resonators can be reduced.
As the dielectric member 1, a material, such as alumina, having a small dielectric constant and low loss is used, the size of a resonator is increased but a large no-load Q value for the resonator can be obtained.
As the support member 3 of each of the specific examples, polytetrafluoroethylene whose relative dielectric constant is 2 is used as an example. However, a material for the support member 3 is not necessarily limited to polytetrafluoroethylene, but other materials which can support and fix the dielectric member 1 may be used. However, the dielectric constant of the support member 3 is preferably lower than that of the dielectric member 1. Actually, assume that a dielectric member having a relative dielectric constant of 20 or more is used as the dielectric member 1. If a material having a relative dielectric constant of 15 or less is used as the support member 3, more preferable properties can be achieved.
Moreover, in each of the embodiments except for the ninth embodiment, the structure in which the support member 3 is filled in spaces in the shielding conductor 2 has been described. However, the structure of a support member for supporting a dielectric member of the present invention is not necessarily limited to the structure, but the structure of the support member for supporting a dielectric member of the ninth embodiment may be applied to the other embodiments.
Moreover, a duplexer for separating transmission/reception signals having different frequencies can be formed by connecting the bandpass filter and the band stop filter (notch filter) which have been described in each of the embodiments by a branch line formed of a microstrip-line or the like. In this case, a duplexer can be obtained by input/output coupling each of two bandpass filters, one of which has its center frequency around its transmission frequency, and the other of which has its center frequency around its reception frequency, with a branch portion of a branch transmission line having an appropriate phase shift amount. Furthermore, in order to satisfy desired specifications, band stop filter can be connected with the bandpass filter in series and thereby the attenuation in the cross-band can be increased.
Moreover, in each of the above-described embodiments, the case in which the 26 GHz band is a designed frequency band has been described as an example. However, the frequency band does not have to be the 26 GHz band. If the dimensions of the dielectric member are changed according to a desired frequency, the present invention is applicable in a wide frequency range. Specifically, if a material having a relative dielectric constant of about 20–40 is used for a resonator, the width of the resonator is in a range from 0.1 mm to 10 mm in a frequency range from about 5 GHz to 100 GHz. Thus, the high-frequency circuit device has an appropriate size, and therefore this is convenient where the structure of the present invention is used. More specifically, in a frequency range of 20–70 GHz, if the dielectric member is formed of a low-loss ceramic material of
Furthermore, in each of the above-described embodiments, the two transmission lines 4 are provided on the common earth conductor layer 9. However, a transmission line of the high-frequency circuit device according to the present invention is not necessarily limited to this structure.
Moreover, in each of the above-described embodiments, the example in which a microstrip-line or a coplanar line is used for the transmission lines 4 has been described. However, the transmission lines 4 in the high-frequency circuit device or high-frequency circuit module of the present invention are not limited to the embodiments.
As has been described, if any one of the structures according to the present invention is used, a small size high-frequency circuit device which has a simplified structure and allows a resonant operation with a high Q value can be obtained. Specifically, if the present invention is applied to a resonant circuit such as a resonator or a filter in a millimeter wave band, higher effects of the present invention can be attained.
Furthermore, a high-frequency circuit module made by applying the high-frequency circuit device is formed utilizing the small size and high Q value characteristics of the high-frequency circuit device, and thus a small size, low-loss high-frequency circuit module which exhibit great functions can be obtained.
INDUSTRIAL APPLICABILITYA high-frequency circuit device or a high-frequency circuit module according to the present invention is applicable to
1. A high-frequency circuit device of a signal transmitting/receiving apparatus in an FWA (fixed wireless access) system using a millimeter wave or a microwave
2. A high-frequency circuit portion of a terminal and a base station in a mobile communication system (e.g., cellular phone)
3. A circuit dealing with a high-frequency modulation signal in an optical communication system
4. A high-frequency circuit portion of a wireless LAN apparatus
5. A high-frequency circuit portion in an inter-vehicle or roadside-to-vehicle communication system
6. A high-frequency circuit portion in a millimeter wave radar system or the like.
Claims
1. A high-frequency circuit module characterized in that the high-frequency circuit module includes:
- a plurality of high-frequency circuit devices; and
- a phase shift circuit provided between adjacent ones of the plurality of high-frequency circuit devices;
- each said high-frequency circuit device includes: at least a dielectric member which can create a resonant state of an electromagnetic wave; a support member which surrounds the dielectric member and has a lower dielectric constant than that of the dielectric member; a shielding conductor surrounding the support member; at least a transmission line including a strip conductor disposed to face part of the dielectric member, an earth conductor layer disposed to face the strip conductor, and a transmission-line substrate interposed between the strip conductor and the earth conductor layer; and a coupling probe which is connected to the transmission line and has the input/output coupling function of input/output coupling with the dielectric member by an electromagnetic wave,
- the dielectric member is excited in the TM11δ mode when it has a rectangular cross section or in the TM01δ mode when it has a circular cross section, and
- the transmission line of each said high-frequency circuit device is connected to the phase shift circuit.
2. The high-frequency circuit module of claim 1, characterized in that the respective center frequencies of the plurality of high-frequency circuit devices when each of them is in a resonant state are different to each other.
3. The high-frequency circuit module of claim 1, characterized in that the phase shift circuit is connected to an antenna.
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Type: Grant
Filed: Jul 21, 2005
Date of Patent: Jun 6, 2006
Patent Publication Number: 20050253672
Assignee: Matsushita Electric Industrial Co., Ltd. (Osaka)
Inventors: Akira Enokihara (Nara), Hideki Namba (Kyoto), Toshiaki Nakamura (Nara)
Primary Examiner: James H. Cho
Attorney: Harness, Dickey & Pierce, P.L.C.
Application Number: 11/186,109
International Classification: H01P 7/10 (20060101); H01H 5/12 (20060101);
